Hi,
This patch tries to implement division with multiplication by
reciprocal using vrecpe/vrecps
with -funsafe-math-optimizations and -freciprocal-math enabled.
Tested on arm-none-linux-gnueabihf using qemu.
OK for trunk ?
Thank you,
Prathamesh
2015-07-28 Prathamesh Kulkarni <prathamesh.kulka...@linaro.org>
Charles Baylis <charles.bay...@linaro.org>
* config/arm/neon.md (div<mode>3): New pattern.
testsuite/
* gcc.target/arm/vect-div-1.c: New test-case.
* gcc.target/arm/vect-div-2.c: Likewise.
diff --git a/gcc/config/arm/neon.md b/gcc/config/arm/neon.md
index 654d9d5..28c2e2a 100644
--- a/gcc/config/arm/neon.md
+++ b/gcc/config/arm/neon.md
@@ -548,6 +548,32 @@
(const_string "neon_mul_<V_elem_ch><q>")))]
)
+(define_expand "div<mode>3"
+ [(set (match_operand:VCVTF 0 "s_register_operand" "=w")
+ (div:VCVTF (match_operand:VCVTF 1 "s_register_operand" "w")
+ (match_operand:VCVTF 2 "s_register_operand" "w")))]
+ "TARGET_NEON && flag_unsafe_math_optimizations && flag_reciprocal_math"
+ {
+ rtx rec = gen_reg_rtx (<MODE>mode);
+ rtx vrecps_temp = gen_reg_rtx (<MODE>mode);
+
+ /* Reciprocal estimate */
+ emit_insn (gen_neon_vrecpe<mode> (rec, operands[2]));
+
+ /* Perform 2 iterations of Newton-Raphson method for better accuracy */
+ for (int i = 0; i < 2; i++)
+ {
+ emit_insn (gen_neon_vrecps<mode> (vrecps_temp, rec, operands[2]));
+ emit_insn (gen_mul<mode>3 (rec, rec, vrecps_temp));
+ }
+
+ /* We now have reciprocal in rec, perform operands[0] = operands[1] * rec
*/
+ emit_insn (gen_mul<mode>3 (operands[0], operands[1], rec));
+ DONE;
+ }
+)
+
+
(define_insn "mul<mode>3add<mode>_neon"
[(set (match_operand:VDQW 0 "s_register_operand" "=w")
(plus:VDQW (mult:VDQW (match_operand:VDQW 2 "s_register_operand" "w")
diff --git a/gcc/testsuite/gcc.target/arm/vect-div-1.c
b/gcc/testsuite/gcc.target/arm/vect-div-1.c
new file mode 100644
index 0000000..e562ef3
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/vect-div-1.c
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target arm_v8_neon_ok } */
+/* { dg-options "-O2 -funsafe-math-optimizations -ftree-vectorize
-fdump-tree-vect-all" } */
+/* { dg-add-options arm_v8_neon } */
+
+void
+foo (int len, float * __restrict p, float *__restrict x)
+{
+ len = len & ~31;
+ for (int i = 0; i < len; i++)
+ p[i] = p[i] / x[i];
+}
+
+/* { dg-final { scan-tree-dump-times "vectorized 1 loops" 1 "vect" } } */
diff --git a/gcc/testsuite/gcc.target/arm/vect-div-2.c
b/gcc/testsuite/gcc.target/arm/vect-div-2.c
new file mode 100644
index 0000000..8e15d0a
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/vect-div-2.c
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target arm_v8_neon_ok } */
+/* { dg-options "-O2 -funsafe-math-optimizations -fno-reciprocal-math
-ftree-vectorize -fdump-tree-vect-all" } */
+/* { dg-add-options arm_v8_neon } */
+
+void
+foo (int len, float * __restrict p, float *__restrict x)
+{
+ len = len & ~31;
+ for (int i = 0; i < len; i++)
+ p[i] = p[i] / x[i];
+}
+
+/* { dg-final { scan-tree-dump-times "vectorized 0 loops" 1 "vect" } } */
